The subject invention relates generally to combustors. More particularly, the subject invention relates to cooling of combustion liners of combustors.
Air management is an important consideration in combustor design. Air streams provide an oxidizer for a combustion process and also provide cooling to hot components of the combustor. Seals are typically provided between various components of the combustor to prevent air from leaking into the combustor at unwanted locations. These seals typically include C-Rings, fingered hula rings, cloth seals, and the like, and are subjected to high temperature and pressure as well as high gradients of pressure and temperature across the seals. In modern combustors, high flame temperatures drive a need to actively cool virtually all metal surfaces of the combustor. One method of actively cooling the combustor components in the area of a liner hula seal is to direct cooling air within cooling channels formed between a seal support and one or more of the combustor components to convectively cool the components. Cooling air typically enters the cooling channels through a series of holes in the seal support at an upstream end of the seal support. The cooling air flows within the cooling channels through an entire length of the seal, thereby cooling the first combustor component by convective heat transfer. As the cooling air flows along the channels, however, its efficiency in cooling the component decreases. To counter the loss of efficiency, larger amounts of cooling air are directed through the cooling channels to provide adequate cooling of the component. In combustors, especially those utilized in lean premixed gas turbine engines it is desirable to reduce the amount of air used for cooling to increase the amount of air directed through the fuel nozzles thereby achieving a uniform, lean-premixed fuel to air ratio to increase combustor performance.